Because of its beneficial characteristics, epoxy resin has been in broad use in the coating, adhesion, civil engineering, and building industries. However, since most of the compositions so far available are of the two-component type, they have the drawback of poor workability. To provide a one-component (type) composition, there have been developed several alternative techniques such as the method using a latent curing agent, e.g. dicyandiamide, as a curing component, the method using a catalyst adapted to generate an active group upon exposure to ultraviolet radiation to cure epoxy resin, or the method using an acid anhydride type curing agent. However, these methods require either a heating step or an irradiation equipment.
To provide a one-component (type) room temperature cure system for overcoming the above drawback, a method is known in which a ketimine is used as a curing agent to produce an amine on contact with external moisture and thereby cure epoxy resin, but this technique has the disadvantage of retarded cure, poor storage stability, and excessive post-cure hardness which call for critical control over the level of addition.